1. Field of Invention
The present invention relates to wireless communications. More particularly, the invention is related to a system for improving the transmission of information via short-range communication through an improved multiple antenna arrangement for expanding the otherwise limited operational coverage area of a short-range communication source.
2. Description of Prior Art
A wireless communication device (WCD) may communicate over a multitude of networks. Cellular networks facilitate WCD communications over large geographic areas. For example, the Global System for Mobile Telecommunications (GSM) is a widely employed cellular network that communicates in the 900 MHZ-1.8 GHZ band in Europe and at 1.9 GHZ in the United States. This system provides a multitude of features including audio (voice), video and textual data communication. For example, the transmission of textual data may be achieved via the Short Messaging Service (SMS). SMS allows a WCD to transmit and receive text messages of up to 160 characters. It also provides data transfer to packet networks, ISDN and POTS users at 9.6 Kbps. While cellular networks like GSM provide a global means for transmitting and receiving data, due to cost, traffic and legislative concerns, a cellular network may not be appropriate for all data applications.
Bluetooth™ is a short-range wireless network technology quickly gaining acceptance in the marketplace. A Bluetooth™ enabled WCD may transmit and receive data at a rate of 720 Kbps within a range of 10 meters, and may transmit up to 100 meters with additional power boosting. A user does not manually instigate a Bluetooth™ wireless network. A plurality of devices within operating range of each other will automatically form a network group called a “piconet”. Any device may promote itself to the master of the piconet, allowing it to control data exchanges with up to seven “active” slaves and 255 “parked” slaves. Active slaves exchange data based on the clock timing of the master. Parked slaves monitor a beacon signal in order to stay synchronized with the master, and wait for an active slot to become available. These devices continually switch between various active communication and power saving modes in order to transmit data to other members of the piconet.
More recently, manufacturers have begun to incorporate various devices for providing enhanced functionality in a WCD (e.g., hardware components and software for performing close-proximity wireless information exchanges). Sensors and/or readers may be used to read visual or electronic information into a device. A transaction may involve a user holding their WCD in proximity to a target, aiming their WCD at an object (e.g., to take a picture), sweeping the device over a tag or document, etc. Machine-readable technologies such as radio frequency identification (RFID), Infra-red (IR) communication, optical character recognition (OCR) and various other types of visual, electronic and magnetic reading are used to quickly input desired information into the WCD without the need for manual entry by a user.
Short-range communication strategies are ideal for business entities seeking to reach information consumers in a designated geographic area. Short-range communications are mostly unregulated, and are generally a cost-effective solution for making data available to a potential recipient. For example, a business may set up a local access point to service customers that come within proximity of the access point. The Nokia Local Marketing Solution and ijack™ by TeliaSonera Finland Oyj are two examples of these local information delivery systems. These services use hardware access points communicating via Bluetooth™ to create piconets including accessible devices that come within transmission range. The service point becomes the master device, and may download price, coupon, show time, date, reservation information, etc. to a potential client. In another application, these systems may also be used to impart work-relevant data to employees or educational information to students, etc. While these systems may work automatically to impart desired information to a consumer, they are limited by the time required to both establish a network and download content. Often, an information consumer will not remain within range of an access point long enough to receive all of the information to be delivered by the device (e.g., a person strolling by a storefront), defeating the primary purpose of establishing the service point.
An alternative to downloading all of the desired information via short-range communication at the time of first contact would be to simply download a pointer, bookmark, indicator, link, etc. to the desired information. The downloaded pointer might include a website address (URL), email address, phone number, etc. that would in turn allow the device user to obtain the body of the desired information at a later time, for instance, from a dedicated short-range service point, via long-range data communication, via a wired internet connection, via a telephone, etc.
In at least one example of short-range machine-readable communication, RFID may be employed to convey several kilobytes worth of data to a reading device in a relatively short amount of time. In addition, a passive RFID transponder or “tag” does not require its own power source. The tag receives power from the reading device. Therefore, the passive tag may be imbedded in any manner of structure such as a poster, display, standee, doorway, wall, etc. A user passing near the tag may manually or automatically read the tag and receive a response including desired information in a relatively short amount of time.
Near Field Communication (NFC) Technology An RFID transponder and corresponding RFID reader constitute a one-way “listening” system that can be used, for example, in a read-only identity card that contains the user's ID. More sophisticated RFID systems may use Near Field Communication (NFC) technology for two-way “read-write” communications. NFC is different from other contactless or RFID technologies in that it has a very short operating distance and also allows two devices to conduct interactive communications. The effective distance of an NFC solution depends on the tag design and the reader, but is typically less than a few centimeters. Near Field Communication (NFC) is a combination of contactless identification and interconnection technologies that enables short-range communication between personal electronic devices. It combines the functions of a contactless reader, a contactless card and peer-to-peer functionality on a single microchip in the NFC communication logic. NFC technology operates in the 13.56 MHz frequency range and is standardized in ISO 18092 and ISO 21481, ECMA (340, 352 and 356) and ETSI TS 102 190. NFC is also compatible with contactless smart card infrastructure based on ISO 14443 A.
ISO/IEC 18092:2004 defines communication modes for Near Field Communication Interface and Protocol (NFCIP-1) using inductively coupled devices operating at the center frequency of 13.56 MHz for interconnection of computer peripherals. It also defines both the Active and the Passive communication modes of NFCIP-1 to realize a communication network using Near Field Communication devices for networked products and also for consumer equipment. This International Standard specifies modulation schemes, codings, transfer speeds and frame format of the RF interface, as well as initialization schemes and conditions required for data collision control during initialization. Furthermore, this International Standard defines a transport protocol including protocol activation and data exchange methods. Information interchange between systems includes agreement between the interchange parties upon the interchange codes and the data structure.
In both RFID and NFC systems, the already short effective communication range of the reader/tag transponder may be further limited by the configuration or composition of the structure in which it is embedded. Certain materials may interfere with radio frequency waves, requiring a user to come closer to the tag in order to make contact. The resulting situation may create a “traffic jam” of users trying to get into the same area in order to receive the desired information. Therefore, what is needed is a way to extend the effective range of the machine-readable data so that a plurality of data users over an extended effective range may receive information from the same tag.
A further problem arises for combined RFID and NFC systems where both RFID listening functions and NFC read-write functions are to be available in the same NFC communication logic. An example RFID listening function would be a read-only user ID card application where the reader merely reads the user's ID from the NFC communication logic. An example NFC read-write function would be an interactive banking application where account balances are first read from the NFC communication logic and then updated and written back into the NFC communication logic by the reader. When a single NFC communication logic has both RFID and NFC functionalities, the antenna tuning and usability constraints are different for the two functions. For the NFC reader-writer function, the distance between the reader antenna and the NFC communication logic antenna is intended to be a short distance (e.g., less than two centimeters) or actual physical contact between the reader and the NFC communication logic. For the RFID listening function, the distance between the reader antenna and the NFC communication logic antenna is intended to be a longer distance of several centimeters. A further complicating factor is that different RFID listening applications may require different minimum separation distances between the reader and the NFC communication logic. For example, the Mastercard application currently requires a minimum of 4 centimeters separation distance from either side of the NFC communication logic card to the reader, whereas the Japan Railways Suica card application requires a minimum of 10 centimeters separation distance from the NFC communication logic card to the reader. This creates a problem where the same NFC communication logic is intended to be used for different RFID listening applications that require different minimum separation distances between the reader and the NFC communication logic.
Various methods are known in the art for increasing the range of a machine-readable tag via extended antenna configurations. However, these configurations often involve a complex antenna structure hardwired to the tag intended to handle only one reading device at a time. What is needed is a method including some intelligence for determining the source of a plurality of reading signals and for adjusting the antenna system to account for these multiple readers. The system must be able to select between active sources in order to return desired information back to a reader while managing the loading of the antenna system.